1. Field of the Invention
The present invention relates to an anodic bonding method, an anodic bonding jig and an anodic bonding apparatus.
2. Description of the Related Art
Conventionally, in manufacturing a sensor, a piezoelectric vibrator or the like, a known package product includes a package in which a cavity is formed between a plurality of substrates bonded to each other.
For a package in such a package product and a method for manufacturing the package, Patent Document 1 describes a package manufactured by stacking and bonding substrates, for example. According to the package described in Patent Document 1, a space within the package can be airtightly sealed.
Also, Patent Document 1 discloses an anodic bonding method as a method of bonding substrates, in which a metal or semiconductor, such as aluminum, titanium, tantalum and silicon, can be used as a bonding layer.
In this case, when substrates to be anodically bonded as above are aligned with each other and placed on a base, and then an anodic bonding jig is placed, the substrates may become misaligned with each other.
For a conventional anodic bonding jig, the alignment is performed based on alignment marks on the substrates. However, during the time from when the substrates are accurately stacked based on the alignment marks till when pressurizing is started, the alignment marks are hidden, so there is no way to detect the above-described misalignment, then anodic bonding is performed while the misalignment remains. So, when a misalignment exceeding the tolerance occurs, all products formed on those substrates may be defective.
In order to address such a problem, an anodic bonding jig having a hole formed so as to pass through the jig from front side to back side has been proposed. For example, according to the proposal, the positions of the alignment marks can be recognized through the hole provided in the anodic bonding jig, which allows correction of a misalignment occurring in the substrates to be anodically bonded even after the anodic bonding jig is placed.    Patent Document 1: Japanese Patent No. 3621435
However, even for the conventional anodic bonding jig having the hole to align the positions of the alignment marks as above, since uniform pressure needs to be applied to the substrates, there is a limit to the size of the hole, which raises a problem of requiring a large amount of time and effort to align the alignment marks with the hole.